Derivatives

protandry

Under natural photoperiodic conditions protandry in hermaphrodite disc flowers of sunflower is determined by the different elongation rates of the style and filaments.

The temporal aspects of stigma receptivity and pollen longevity were investigated in relation to protandry (the occurrence of anther dehiscence prior to stigma receptivity) and breeding system.

Predictions from the above hypotheses are not mutually exclusive, and associations between protandry and sexual dimorphism may be promoted by complex interactions between the suggested mechanisms acting in concert.